Switch-actuating mechanism



April 15, 1958 F. H. HOFlNG SWITCH-ACTUATING MECHANISM Filed NOV. 17,1955 43 INVENTOR. FREDERICK H. HOFING .c'. 4/ ATTORNEYS United StatesPatent at tel.

SWITCH-ACTUATING MECHANISM Frederick H. Hating, Sharpsville, Pea,assignor, by mesne assignments, to the United States of America asrepresented by the Secretary of the Navy Application November 17, 1955,Serial No. 547,585

Claims. (Cl. 200-31) This invention relates to switch mechanisms andmore particularly to an improved switch mechanism of the rotary camoperated type.

Switch mechanisms of the particular class to which the present inventionrelates usually comprise a row of several switches of over-centersnap-action type and a multi-section rotary cam assembly, together withcam-followers which actuate the several switches in accordance with theparticular time-contour characteristics of the rotary cams. Means areoften provided for adjusting the makebreak throws as imparted by theswitch mechanism, and for variably positioning and locking the cams sothat their angular relationship can be pre-set to precisely time andproperly sequence the actuation of the several switches, and prior artswitch mechanisms are generally satisfactory in these respects in usualapplications. It has been found, however, that conventional switch mechanisms of the above-described character, when employed in ordnanceequipment subject to shock and vibration during operation, arevulnerable to the extent that such environments may cause the switchesto be spuriously actuated by the cam-followers with resultantmalfunction or improper operation of the said ordnance equipment.

It is therefore the principal object of the present invention to providea rotary cam-operated switch mechanism having essentially positive andreliable actuation characteristics in adverse shock and vibrationenvironments.

A further object is to provide a switch mechanism in which shock andvibration forces, tending to displace and therefore operate the switchactuator, are resiliently opposed and defeated.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as .the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is a side elevational view of a switch mechanism embodying thepresent invention, certain parts broken away to show the constructionmore clearly; and

Fig. 2 is a front elevational view taken along section line 2-2 of Fig.l to provide a better understanding of the switch mechanism assembly.

The invention will be described in connection with a particularembodiment shown as having two switches actuated by a like number ofrotary cams. It will be understood, however, that the present inventionis applicable to assemblies having any number of switches and cams.Considered from a broad standpoint, the invention contemplates amechanism comprising one or more cams which, through followers that arerestricted in displacement inherently and by auxiliary resilientelements, act upon control elements of one or more switches inaccordance with the contour time characteristics of said cams.

Referring now to Figs. 1 and 2, the switch assembly comprises one ormore switches 10 of over-center snapaction type, each having connectionterminals 11 leading ice to various contacts within the switch, and aplunger element 12 which, when depressed, opens the normallyclosedcontacts and/ or closes the normally-open contacts. Such switches, whichare now conventional per se, such as the so-called Micro variety whichare used extensively because of compactness and other attributes, aregenerally quite sensitive in the respects that they may require onlysmall operating forces, say of the order of one ounce, and actuation byplunger element displacements which may be minute, say of the order of afew hundredths of an inch. These switches are normally enclosed in amolded plastic case of configuration substantially as here illustrated,thus entirely sealed except for the small clearance necessary toaccommodate movement of the plunger element 12. The switches 10 aremounted upon a bracket 13 by means of machine screws 14 which extendthrough apertures (not shown) provided in the casings of switches 10 andinto threaded holes 15 which are provided in a thickened supporting arm16 of the bracket, as shown. Spacers 17 serve to align and center theplunger elements laterally with respect to the cam-followers andassociated actuating elements later described. Lock-washers 18 may beemployed as shown to assist in maintaining switches 10 securely afiixedto the bracket and therefore in fixed relationship to the said actuatingelements. Also supported by bracket 13 are cam-follower arms 19 andswitch-actuators 20, the latter being disposed between the cam-followerarms 19 and the switch plunger elements 12. Cam-follower arms 19 are oflaminated structure, each comprising an elongated leaf 21 secured at itslower end to a cross-piece 22 mounted upon the bracket, and a rollersupport 23 which may be secured to the upper stretch of leaf 21 by spotwelding at its extremities. A roller 24 designed for cam-following isjournaled for rotation, upon roller support 23, between two fingers 25(of which one is visible, the other in frontal alignment therewith inFig. 1) which are conveniently made an integral part of the rollersupport as illustrated. Crosspiece 22 i here shown as a separable partof bracket 13, secured thereto by means of machine screws 26 of whichonly one is visible in Fig. 1. The cam-follower arms are secured tocross-piece 22 in alignment with switches 10 to confront their plungerelements 12. An elongated aperture (not shown), at the lower end ofcam-follower arm 19, accepts fastening screw 27 and permits adjustmentof roller height relative to the corresponding cam axis.Switch-actuators 20 are similarly of elongated configuration, having abore formed at the lowermost end 23, by means of an integralconvolution, so that the actuator may be actuated for pivotal movementupon a rod 29 as shown. The ends of rod 29 may he held by press inopposed walls 30, 31 of bracket 13, in such location that rod 29 isdisposed between the cam follower arms 19 and the row of switches 10 andin parallel relation thereto. Each of the switch-actuators 20 isresiliently urged toward its cam-follower arm 19 by means of a wirespring 32 having a convolution 33 intermediate of its length, whichenables the spring to be accepted by and mounted upon rod 29, a leg 34disposed to bear against floor 35 of the bracket 13, as a spring stopmeans, and an arm 36 conformably bent to bear against theswitch-actuator 20 along a line beyond rod 29. Also mounted upon rod 29are spacers 37 which serve to position and maintain the switch-actuatorsin confronting alignment with the switches 10.

Switch-actuator 20 further carries an adjusting screw 38 having threadedengagement with and extending through a boss 39 and through aregistering aperture in the upper end of the switch-actuator 20 to whichboss 39 is secured. A nut 40 is provided as shown for adjustment lockingpurposes.

Bracket 13 is provided with a support member 41 which 3 is secured to atimer base 42 by means of machine screws 43 as shown. All of the switchmechanism elements are carried by bracket 13, except for the rotary camassembly 44, the latter being supported upon a shaft 45, journaled bybearing 46 provided in a side member 47 which is secured to the timerbase 42. Shaft 45, adapted to be rotated by an electrical timer motorincluding a gear reduction unit (not shown) and held againstlongitudinal displacement by any conventional means, carries rotarydisclike cams here shown as two .in number, designated 48 and 49, eachhaving a peripheral contour including suitably proportioned fall, innerdwell, rise and outer dwell portions to yield desired time displacementcharacteristics or". associated follower elements. The member 50 whichis secured to shaft 45 in the particular embodiment here illustrated hasno direct bearing upon the present invention and may therefore beregarded simply as a spacer element which, together withspacing collars51 and '52, suitably position the cams 48, 49 along the shaft so thatthey properly confront their respective rollers 24. The assembly of camsand spacers is held together by means of a circular nut 53 which may beheld to shaft 45 by one or more set screws 54 as indicated. The camassembly also includes means, such as spline elements (not shown), whichmaintain the rotary cams in a predetermined angu lar relationship uponthe shaft.

In the above-described switch mechnism, assuming an angular position ofshaft 45 at which roller 24 is in an inner dwell portion of cam 48 sothat switch is in a released condition, depression of plunger element 12by spurious actuating forces is resisted by the mechanical restraintafforded by the combination of switch-actuator 20, tensioned by means ofwire spring 32, and cam-follower arm 19, having restricted angularmovement and which also is acted upon by'wire spring 32 through theintermediary of screw 38. Screw 38 further enables adjustment of theon-oif action of plunger element '12 relative to cam rotation. In thisrespect, one desirable type of adjustment, readily obtainable, causesswitch operation (in going from inner to outer dwell) and switch release(in going from outer to inner dwell) to be effected by equal radialdisplacements of the cam roller.

It will be understood that the present invention, While of particularimportance in connection with switches of over-center snap-action typeas here described, is also fully applicable for use in connection withswitches of other types, and that other modifications and variations ofthe present invention are possible in the light of the above teachings.It is therefore to be understood that within the scope of the appendedclaims the invention may be practiced otherwise than as specificallydescribed.

What is claimed is:

1. In a rotary-cam switch-actuating mechanism comprising an electricalswitch having a control element and adapted to be operated bydisplacement of said control element, a rotatable shaft carrying arotary cam, and cam-follower means supported in operative relation tosaid rotary cam, wherein said rotary cam is adapted upon rotation toprovide displacements of said cam-follower means of magnitude suitablefor operation of said control element, in combination, a switch-actuatormember supported in confronting relationship to said switch controlelement for imparting switch-actuating displacements thereto, meansproviding an adjustable displacement-link between said switch-actuatormember and said cam-follower means, spring means acting upon and urgingsaid switch-actuator member in a direction to maintain said cam-followermeans in operative engagement with said rotary cam, and means supportingsaid electrical switch with its control element in contact with and inposition to be operated by displacement of said switch-actuator member.

2. A rotary-cam switch-actuating mechanism as defined in claim 1,wherein said electrical switch is of over-center snap-action typecontrollable by a spring-return plunger element.

3. A rotary-cam switch-actuating mechanism as defined in claim 1,wherein said cam-follower means comprises an elongated leaf structuresupported at one end thereof and carrying a cam-following element at theother end thereof.

4. A rotary-cam switch-actuating mechanism as defined in claim 1,wherein said switch-actuator member comprises an elongated elementpivoted at one end thereof, carrying said adjustable displacement-linkat the other end thereof, and wherein the portion of saidswitch-actuator member bearing against said switch control element liesintermediate said two ends.

'5. A rotary-cam switch-actuating mechanism as defined in claim 1,wherein said adjustable displacement link is a screw element threadedlyengaged with said switch-actuator member and having an end thereof incontact against said cam-follower means.

References Cited in the tile of this patent UNITED STATES PATENTS2,366,454 Pattee Jan. 2, 1945 2,386,760 Warner Oct. .16, 1945 2,444,146Schellens June 29, 1948 2,489,422 Kuhn Nov. 29, 1949 2,503,082 TuttleApr. 4, 1950 2,553,299 Carr May 15, 1951

